As prior (background) art of this technical field, there exits Patent Literature 1 cited below.
Patent Literature 1 includes the following description: “After metals, ceramics, or metal salts are left for a predetermined time period in the environmental atmosphere as the measuring object, gas components that have been adsorbed thereby are analyzed. In particular, porous metals or ceramics (transition metal oxides) have a high selective absorptivity for NOx; porous ceramics (rare-earth element oxides) have a high selective absorptivity for CO2; and specific chlorides such as copper chloride and silver chlorides have a high selective absorptivity for SO2.” Patent Literature 1 also includes descriptions of a testing kit that houses specimens of these materials in a case; and a testing kit protective case, umbrellas, and a forced air feeder for commercializing the testing kit.
FIGS. 11A and 11B show a typical prior art environment monitoring apparatus. FIGS. 11A and 11B are a side view and a top view, respectively, showing the internal structure of a protective case for the prior art environment monitoring apparatus.
In the prior art environment monitoring apparatus 100, a vent duct 112r of the protective case 112 houses specimens 111 of copper (111a), silver (111b), aluminum (111c), iron (111d), and an iron nickel alloy (111e), for example.
When a corrosive gas 106 that is present in the ambient environment is allowed to flow in the direction indicated by a white arrow, corrosive substances contained in the corrosive gas 106 adhere to the surfaces of the specimens 111 and discolor them. If the protective case 112 is made of a transparent material, the discoloration of the specimens 111 can be visually inspected (seen through) from outside of the protective case 112.
The specimens 111 collected after exposure to the corrosive gas 106 for the predetermined time period are measured for the degree of corrosion over predetermined regions by gravimetric method, by quantitative analysis for corrosive gas elements using fluorescent X-rays, and by film thickness measuring through constant-current electrolysis.
For example, Patent Literature 1 reports that the corrosive gas concentration in the environment as the measuring object can be estimated from the results of the quantitative analysis of corrosive gas elements in corrosion products formed on the surfaces of the metal specimens 111 due to the presence of the corrosive gas 106. It is also reported that the corrosiveness of the environment of interest is categorized depending on the thickness of the corrosion product on a copper plate exposed for one month to the environment as the measuring object in accordance with the IEC654-4 standard, ISO11844-1 standard, ISO9223 standard, and ISA71.04 standard.
Specifically, the specimens 111 exposed for the predetermined time period to the atmosphere as the measuring object are analyzed by fluorescent X-ray analysis and X-ray luminous energy analysis for corrosive gas components (sulfur in sulfur oxides and sulfides, nitrogen in nitrogen oxides, and chorine in chlorides) in the corrosion products formed on the surfaces of the specimens 111. Also, the corrosive gas composition is analyzed by color specification data analysis in terms of brightness, hue, and saturation of the corrosion products.
Furthermore, Patent Literature 1 discloses a method which, where it is desired to shorten the time of exposure to the atmosphere of the ambient environment, involves forcibly feeding the corrosive gas of the ambient atmosphere to the specimens 111 to promote the corrosion reaction thereof (see paragraph 0050, FIG. 8, of Patent Literature 1).
In the prior art environment monitoring apparatus 100, the corrosive gas 106 in the ambient environment is allowed to flow toward or diffuse around the specimens 111 via an opening 112k of the protective case 112, with or without fans.